The yellow warning said fog and patches of freezing fog are possible today and on Christmas day.

This may lead to reduced visibility and delays on the roads, buses and train services. There is also a chance of delays or cancellations to flights.

The warning, which says the fog may be dense in some places, runs from 3pm today until 11am tomorrow.

It read: "Fog or freezing fog patches, dense in places, becoming widespread and then slow to clear for some on Christmas Day."

Cambridge can expect a high of 5C today and a low of 2C. Temperatures will warm up slightly on Christmas with a high of 8C and a low of 7C.

Fog lingers over the River Cam, near Clare College (Image: Chris Radburn/PA Wire)

What to expect from the warning, according to the Met Office

The Met Office said: "Fog or freezing fog patches will quickly become more widespread later on Christmas Eve, and will also be dense in places. Not everywhere will see fog, but where it does form, the visibility may fall to around 50 metres at times.

"Fog will tend to thin and lift in western and some central areas of England overnight, but will be slow to clear on Christmas Day in the east, perhaps persisting for much or all of the day in parts of Eastern England."

How to drive safely in fog

According to the Highway Code, you must use headlights when visibility is seriously reduced - generally when you cannot see for more than 100 metres.

When there’s fog around, make sure you’re familiar with how to operate your front and rear fog lights.

If your car has automatic lights, remember to check the lights are on, as they may not be automatically activated in foggy conditions. However, do not use full beam lights, because the fog reflects the light back, reducing visibility even further.

Follow the ‘two-second rule’ to leave sufficient space between you and the car in front.

If visibility is very limited, wind down your windows at junctions and crossroads to allow you to listen out for approaching traffic. If you really cannot see, you should consider stopping until it is safe to continue.

If your car is fitted with air conditioning, use it, as it will stop the windows from misting up. Ensure the heater is set to windscreen de-misting and open all the vents.

If the fog is so severe that you’re struggling to see other vehicles, switch on your fog lights.